Horodruin

Horodruin is a tool to synchronize the content of multiple folders at once. It provides several filtering options based on file masks, access rights and other details. Unlike similar products, it does not use a specified target folder but synchronizes folders among each other and you can limit copy actions with use of the masks or access rights. Horodruin can be a little difficult to get started with, but quite flexible once you get familiar with it. The interface provides a preview that shows you which files are synchronized and which are not.